Perhaps you should try some spelling variations:
"su sach ngonh ky thuat co hoc" » "su sach ngon ky thuat co hoc", "su sach ngan ky thuat co hoc", "su sach nganh ky thuat co hoc", "su sach ngonh ky thuat do hoc", "su sach ngonh ky thuat o hoc", "vu sach ngonh ky thuat co hoc"
"so sach ngoc hai thuat hoa hoc" » "so sach ngon hai thuat hoa hoc", "so sach nuoc hai thuat hoa hoc", "so bich ngoc hai thuat hoa hoc", "so sach ngoc phau thuat hoa hoc", "so sach ngoc giai thuat hoa hoc", "so sach ngoc khoi thuat hoa hoc", "so sach ngoc hai thuat toan hoc", "so sach ngoc hai thuyet hoa hoc", "so sach ngoc hai thuat do hoc", "so sanh ngoc hai thuat hoa hoc", "bo sach ngoc hai thuat hoa hoc", "co sach ngoc hai thuat hoa hoc"

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: (("su sach ngonh ky thuat co hoc") or ("so sach ngoc hai thuat hoa hoc"))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("su sach ngonh ky thuat co hoc") OR ("so sach ngoc hai thuat hoa hoc")).
• Removing quotes may allow a broader search: (( su sach ngonh ky thuat co hoc ) or ( so sach ngoc hai thuat hoa hoc )).
• Adding a wildcard symbol may retrieve word variants: (("su sach ngonh ky thuat co hoc") or ("so sach ngoc hai thuat hoa hoc"))*.